Tekken Series,Kazuya Mishima

When Kazuya was a five year old child, he was thrown off of a cliff by his father, who claimed that his son was weak. If Kazuya was to be his father’s successor to the Mishima Zaibatsu throne, he was to not only survive the fall, but climb back up the rocky cliff as well. Kazuya nearly died from the fall, but his survival was assured through a deal with the Devil, who promised him enough power to take his revenge on his father.

It was presumably believed that the demonic power that forms the Devil Gene was introduced in the Mishima family when Kazuya formed the pact with Devil (although Jinpachi Mishima would later acquire a Devil Gene through his own pact with the Devil). This also explains why Jin came in possession of the cursed gene, despite that he never forged any sort of pact with the Devil, for it means that he inherited said gene from Kazuya.

In the years prior to the events of the original Tekken, Kazuya entered martial arts tournaments all over the world, becoming an undefeated champion (only Paul Phoenix ever managed a draw with him.) When the first King of Iron Fist Tournament was announced, Kazuya took the opportunity for vengeance. It is during the tournament that the original game takes place.

before his defeat at the hands of Heihachi, Kazuya became intimate with Jun Kazama, who conceived their son, Jin Kazama.